1. Field of the Invention
The invention relates to a cooling device for a battery, and more particularly, to a cooling device for a battery that is mounted in a vehicle.
2. Description of Related Art
A vehicle that is equipped with a battery and a cooling fan that blows the air in a vehicle interior to the battery is disclosed in U.S. Pat. No. 4,561,743. In the case where the battery is at a high temperature, the cooling fan is operated. Thus, the battery is cooled.
In general, the cooling fan is provided with a bearing portion that supports a rotary shaft for rotating the fan. An oil film of lubricating oil is formed between the rotary shaft and the bearing portion. This oil film prevents the rotary shaft and the bearing portion from coming into contact (metal touch) with each other, thus protecting the bearing portion.
However, with the periphery of (the atmosphere around) the cooling fan at an extremely low temperature, the lubricating oil in the cooling fan exhibits high viscosity, so a sufficient amount of lubricating oil may not be supplied to the bearing portion of the cooling fan. When the cooling fan is operated in this state, the oil film protecting the bearing portion of the cooling fan breaks, and the bearing portion is chipped off through metal touch. As a result, the cooling fan may undergo a failure.